Portable sawing apparatus



` May 2s, 194g.

E. DE v. ToMPKNs PORTABLE SAWING APPARATUS."

Filed April 21,' 1957 i i w INVENTQR BY @@yn ATToRNEYs 5 Sheets-Sheet 1 May 26 1942@ lE'. DEV. TQMPKlNs 2,183,958 w y PORTABLE sAwING Arrnuus v Filed April 21, 1937 f 5 sneetssheet 4 ,6am/w Zl-INVENTOR.

ATTORNEYS.

May'26, 1942/.- y E. DE, y.' TQMPKINS 2,283,958

l l roR'TABLE sum1@ APPARATUS Filed April 21,` 1937 15 sheets-sheet s Patented May 26, 1942 carries4 STTESPATENT ortica,

i 2,283,95851 i roumain sAwING APPARATUS Edward Voe Tompkins, New York, N. Y. Application April 21, 1937, Serial No. l38,093

i2 claims. (C1. 14s-ss) f desired, the gearing also, as well as blowing away the saw-dust, maintaining a super-pressure in the casings of the gearing to prevent the entrance of dirt or dust to the interior of the casings, and

also assisting inthe lubrication of the gearings, all as more fully explained hereafter.

The general object of the present invention is to provide a power-driven portable sawing apparatus which may be embodied in an apparatus powerful enoughl to 4do `the work of sawing relatively large size timber's, while at the same' time so light in weight that it can be readily handled by two men, with little more diiculty than would be the ordinary two-man cross-cut saw, and, also,

' will be much more compact than anything heretofore devised.

A further important object of the present inl vention is to provide an apparatus such as de scribed which will be very durable under the relatively rough treatment; to which 'such an apparatusis subjected in ordinary use and which will allow the ready removal. and replacement of the new blades, as, for example, when they are to be sharpened.

With the above-mentioned general objects in view vand some others which'will be obvious to those skilled in the art from the description herebetween the respective driving means, an important reduction in the length of the apparatus is' inafter, the present invention comprises as its t stantially the same reaction as its companion sawblade in both directions of its movement, in combination with positive means f mechanically coupled directly to the blades and arranged to reciprocate them in opposite directions. simultaneously with equal forces on the-two blades at each instant. As a result of the opposite movements simultaneously of the two saw-blades the material being sawed ordinarily need not be fastened, as it is not subjected to any stress tending to cause displacement in theline of the keri.,

.that the two blades do not cut in identically the same kerf, but as the lever arm of the torque is only equal to the thickness of a single blade, its

effect is negligible, and is overcome by the inertia of the material being sawed and its frictional resistance to sliding angularly on its support..

It is particularly to be noted2 however, that in order to accomplish the desired result the-blades must at all times make their strokes in union, in opposite directions. Attempts have been made heretofore to provide a sawing apparatus with two blades, but such attempts have not been successful because the driving mechanism was not suchvas to insure the synchronism ofthe opposite strokes of the two blades.

Therefore, a further important feature of the present invention is the provision of identical driving means for reciprocating the blades, one

driving meansfor each blade, and the mechanical interconnection of the respective driving means,

so that at all times they are compelled to moveV obtained, as compared .with apparatus having the driving means located beyond the end of and in line with the respective saw-blades. Y

Further important features of the invention -will appear in connection with the description of the best embodiment of the invention illustrated in the accompanying drawings, in which\ Fig. 1 is a side elevation; Fig. 2 a` top plan view; Fig." 3 anA end elevation;-

Fig. 4 a horizontal section on the line,l 4 4,

Fig. 1;

Fig. 5 an enlarged vertical section on the line 5 5, Fig. 1; v

Fig.' 6 a diagrammatic end view of one casing and its enclosed parts, the casing being in section; l

Fig. v'7 a diagrammatic plan view of a pair of Y r f Fig. 10 a plan view of the sawing'apparatus;

provided with a straining orholding device suit- There is, ofcourse, a slight torque due to the fact able for ripping or similar work, and

9 a. section on the line 9 9, Fig. 8,1ooking lfrespective gear casings.

possible to save IFig. 11 an end view of the said straining or holding device. l

The apparatus shown comprises two casings, each containing two sets of epicycloidal gearing for. converting rotary motion` into reciprocatory motion, and two saw-blades having pol-A ished backs in `close' contactwith each lother,

leach endfof each blade extending into the respective casing, in which are twocross-heads, one for each blade, and guides foreach cross-head.

f between the two bearing rings. The outer bear- 1 ing `ring 29 is littedtightly into an opening The gearing is specially `constructed and arl ranged, as more fully described hereinafter. Furthermore, each casing contains driving gearing which is common to the two sets of epicycloidal gearing, this driving gearing having a shaft actuated by the particular rotary motor which is employed, there being one motor for each cas ing, with suitable means convenient to the respective operators for controlling the motor. The motors. may be located, each at one side of the Each gear casing is of any suitable shape so as to enclose its respective epicycloidal gearingy `and also the driving gear therefor. In the particular embodiment illustrated, the said casing is end, the end Wall il of the casing appears generally-circulanwith a generally semicircular portionat the top, as vwill be clear from Fig.` 1. The side walls 2|, conform. to thev outline of the waight. When viewed from one shaped to t the contained parts as closely as 'its respective ,guide bars.

any suitable manner.

'exterior circumferential ball groove orchannel, an outer bearing .ring29 having its inner surface provided with a groove or channel for the balls, and a plurality of balls 30 which are` placed formed in the `respective cross-head, Where it vmay be secured-in any suitable way. Itl will` be noted that the ball-bearing shownand described is of the general type which will resist thrust as well as radial stresses. i l

As there are twg casings, held apart' in any way andeach casing has two cross-heads, there are four cross-heads to be vattached to the two ends of the two sawsone cross-head for each end of each saw. Each end of each -saw 3|, Sla, ,I

- of the saw with two anges, 21h, Figs, 5 .and 8,

which engage thetop and bottom faces, re-

' spectively, of the corresponding cross-head and end walls. Each casing is formed iritwo` parts 7 joined along the middle `-and held together by suitable fastening means. In the constructionl illustrated, the fastening means consists of bolts and nuts, indicatedat 22, Figs. 1 and v5, extending from one endl of the casingto the other end and arrangedto draw the two half-casings together, the `casing Wall being thickened at the pointswhere the bolts are located, these thickene'd portions projecting onl the outside of the` casing, ask indicated at 23, Fig. 3. The holes torthe bolts are formed in the thickenedwall portionsin anyY suitable way, as, for example, by coring them `in the walls when casting'the cas'- ings or by drilling them. Each casing has openings diametrically. opposite each otherand is are held by bolts 21o, extending throughthe respective cross-head and `through both anges, each bolt having 'a nut 21d, as shown inwFig. 8.

The' nuts may be locked by spring lock-washers,

one of which is indicated in Fig. 5. K.

The' cross-heads reciprocate in their respective guides across thev interior of the respective casing, and in the construction shown, each `crosshead, at the limit of its ystroke in each direcf tion, appears outside the casing, which has openings inline with the4 guides, as will be clear from Figs. 4 and 5. VThis arrangement permits the casing to be made small, thus saving weight, While at the same time-allowing the use of a relatively long cross-head.

provided withv flanges, as indicated at 24, one

iange being secured to one casing-half and the other iiange to the other casing-half, these flanges 24, in the vbest embodiment of their-invention being strengthened 'or braced by'suitable bracket-llets' as indicated- 'at 25,` Fig,A 4, the 4flanges 24 and their bracket-fillets 25 being advantageously cast integral with the respective half casing.

lThe cross-head guides .may be Amade of Y"fiatbars, 26, 26a, of `,suitable metal, most advantageously of rolled steel, there being. .four of Vthese bars, each of which is suitably secured to the respective flanges 24, as `by machine screws, most advantageously two `at each end, as indicatedatzsarig. 4.

The cross-head guides in each casing 4serve as 4the runways for two 4cross-heads, which are indicated at 21, 21a, Figs. v4 and 5'. Each, crosshead has two channels'or grooves to receive its respective'pair, of bars lon'V which it slides, the

`Each cross-head is engaged by a driving pin, 32, Fig. 4, cylindrical in cross-section and tting properly into thecentral opening of the respective inner bearing ring, .28. The vdriving pin is carried by a` gear-wheel, which may be termed a planet-wheel, indicated at 34.

v'lhe driving pin, 32, may be mounted on the planetwheel in4 any suitable way.- but in the best embodiment ofthe invention it is. made with' an integral foot, 33, which is, riveted to the planeta-wheel, 34, as shown in Figs. 4 and 6. The

- driving pin, 32, is so located that the longitudinal axis will be at right angles to a' plane of rotation of' the planet-wheel, ,34, andvwill intersect the pitch une of said wheel.`

ThePlanet-wheel, 34,` is revolubly mounted on and carried yaround by a gear wheel, 35, which' may be designated asthe sun-wheel. While the method of mounting the planet-wheel `on the sun-wheel may be carried out in various ways, in

- the ,best embodiment of the invention the planet- Wheel, 34, has a stub-shaft, 36, ilxed to it, and extending ,outward, as shown in Fig. 4. This j shaft has its' longitudinal axis coincident with cross-head` 21 being guided by the bars 26, and` the'companion cross-head 21a being guided by the bars 23a. Each cross-head also, has a bearing to receive a driving or `wrist pin,,more fully.

described hereinafter. While. various. forms of bearings may be employed, the best embodiment ofthe invention comprisesasuitable antifriction wlfriciien bearing. suena bearing is indicated theoentral axis of. the planet-wheel `and enters theinner bearingring, or' sleeve, 31, ofy an antidiagrammatically in Fig. 4 and comprises, in addition torthe sleeve, 31, an outer bearing sleeve, 33, securedin a hub, 33,. carried by the sunwhee1,- 3f.v The bearing sleeves, 31 and 3l, have bearing such as the ball bearing shown in Fig. 8, Vconsisting of an-lnner bearing ring 28, lhaving an raceways for a set of suitable anti-friction devices such as the balls, 40. A suitable, thrust Y bearing may be provided .when desired, as, for

example,l by providing bearing rings, 4| and 42, between the planet-wheel, 34, and the sun-wheel,

35,' as shown in Fig. 4. Each of these rings has a ball-channel and in these channels is located a series of balls, 43. The sun-wheel, 35, is re'- l-irolubly mounted in the casing in any suitable `lway. In the embodiment illustrated in the drawings, the sunwheel is provided with a stubshaft, 44, fixed to it and arranged to rotate in an antifriction bearing carried by the casing. The

`casing Y has a tubular hub, 45, in Awhich is mounted a bearing-support, 46, adjustable in the -hub in the direction of the longitudinal axis of the, stub-shaft, 44, for a. purpose hereinafter explained. Any suitable form of antifriction bearing may be employed. The one illustrated is similar to that described `for the mounting of the planet-wheel, 34. It comprises an inner bearing sleeve, 41, secured to the stub-shaft, 44, an outer bearing sleeve, 4S, secured in the bearing-support, 45, and antifriction devices located between the two bearing sleeves, 41 and 48. As shown, theantifriction devices are balls, 49, in two sets,

While any suitable means may be employedA for rotating the sun-wheels, the construction illustrated in the drawings, is particularly advantageous,`because it permits the two halves `of the casing to be separtedandreplaced with ease and `also provides for connection with the rotary motor at either side of the casing. In the embodiment shown, the driving gearing comprises two gear-wheels, 51, 51a, each meshing with its 17espective sun-wheel, 35, a, as shown in Fig: 5.

Each driving gear wheel 51, 51a, isgflx'ed on its v respective half' of a two-part driving shaft haveach set running 'm channels or ball-races formed in the-respective bearing sleeves. Also, a thrust bearing may be employed, this, -in the present example, comprising two disks, 5!) and 5I, having ball races in which are located balls, 52.

, The bearing-support, 46, may be threaded into the'tubular hub, 45, and may have its outer end closed and provided with a polygonal recess as indicated at 53, Fig.,4, to receive the end of a socket wrench, whereby the bearing-support may be rotated to screw it in or out of the hub. A lock-nut, 54, may be provided on the outer end of the bearing-support,f 46, for a purpose hereinafter explained.

The planet-wheel, 34, is arranged to mesh with an interiorly toothed circular rack, 55, Fig; 4, which is held in place inside its respective casing-half in any suitable way. As shown, the circular' rack, or internal gear ring, 55, is provided with a flange at one side, andmachine screws, 56, pass through the casing side-wall into threaded holes in theiiange.

The gearing thus far described, comprising the sunwheel, 35, including its mounting or journal, the planet-wheel, `34, including its journal, and the internal gear ring or circular rack, 55, constitutes an epicycloidal gear, and the elements are so dirnensioned that the pitch Vdiameter `of the planet-wheel, 34, is one-half the pitch diameter of the internal gear ring or circular rack, 55, so that when the sun-wheel, 35, is revolved by the driving gearing, Aas hereinafter explained, the axis of rotation of the planet-wheel will move orbitally and at the same time `the planet-wheel will be revolved about its axis because of its engagement with the xed circular rack, 55, whereby' the driving pin, 32, will be reciprocated along the diameter ofthe circular rack, 55, in a straight line, thus reciprocating the cross-head, 21, in its guides.

The casing contains two gearing of the kind described, each having its driving pinarra'nged to drive its corresponding cross-head. The arrangement of the parts is such that when one cross-head is at one end of its stroke, the companion cross-head is at the opposite end of the stroke. This is shown, for

. example, in Fig. 4, where the cross-head 21 is at the extreme end of its -stroke to the right, in

epicycloidal trains of e ing its two-parts, 58, 58a, arranged t'o be coupled by a suitable coupling device which will permit the ready separation and replacement of the two parts of the driving shaft, when the halves of the casing are taken apart or put together.

One satisfactory form of coupling for the purposes of this inventionhas the meetings ends of the parts, 58, 58a, of the driveshaft tapered and formed polygonal in cross-section, for example,

square, as shown in Fig. 5, and these ends fit snugly into opposite ends of a socket coupling member B0, which may be secured toone shaft part, for example, the part 58, in any suitable way, as by a pin 6I, passing transversely through the coupling member and shaft part, the ends of the pin 6l, being riveted, if desired.

The driving shaft, formed of the two parts 58, 58a, is suitably journaled in the casing and may be mounted inantifriction bearings. As shown, each bearing has an innerbearing sleeve, E2,.an outer bearing sleeve, 63, and suitable antifriction devices such as balls, 64, held in ball-races or grooves formed in the bearing sleeves.

Each end of the drive shaft projects loutside `the casing and is made polygonal in cross-section,

for` example, square,as shown in Fig. 5. Any suitable compact rotary motor may be employed to rotate the gearing drive shaft. 1n theparticular embodiment illustrated a. rotary motor to be driven by compressed air is illustrated, somewhat diagrammatically, in Fig. 5. This motor, indicated generally at X, has a motor shaft, rc, driven by a rotor x1, xed thereon and having vanes indiciated at :1:2 and exhausts through pipel 2:3, which has an opening to the interior of the casing and a nozzle :c4 at the saw blades. motor shaft is shown as mounted in ball-bearings and is provided with a socket-device :c5 arf ranged to fit on either polygonal end of the gear.

. ing drive-shaft, that end which is not engaged by the motorv being covered by a readily removable cap, 65, Fig. 5, which may be held to the respective end wall ofA the casing by machine screws, 66. By removal of the cap, a socket wrench may be applied to the projecting squared Iend of the drive shaft, in order to turnthe gearing by hand when necessary, as, for example,V

when attaching or detaching a saw-blade to its cross-head, this being possible, because at the two extreme ends of .its stroke each cross-head comes outside its casing enough to allow one of its two blade-holding bolts 21e, to be removed,

The

' firmly therespective yoke devices.

the other bolt of the pair being accessiblewhen the cross-head is moved to the opposite extreme end of its stroke so that it again comes out of the casing on the opposite side.

Ashereinbeforedescribed, there are two casngs, each with its contained duplex epicycloidal gearing ofthe type already described., These casingsmay be held apart in any suitableway,

[even manuallyby the two operators, each of whom may grasp the two handles, 14 and 18 Aof blades, as for example when felling trees. However, in the complete embodiment of the invention, means' are provided for straining or tensioning the blades a predetermined amount. One

such means,` illustrated in Figs. land 2, comprises two yoke-devices 61, arranged to be. se-

cured to the hubs, 45, ofthe' respective casings.

As shown, each yoke deviceisof tubular metal and has one end connected to a split annulus, 68, fitting over the respective hub, 45, of one casing while the. other end enters and is clamped in the split eye, 69a, of a connection 59, which has a split annulus, 69h, surrounding the correspond- 'ing hub of the other casing.

Suitable means are provided for tightening'the split annuli 68 and 69h, such as the bolts and nuts indicated at 10, Fig, l, and for tightening the split eye,`69a,.such as the bolts, 1|.

In this embodiment of the invention, the yokes,

'1.o the casing athis end and pull to tension the sawaccepte d handle, 18, which is advantageously curved, as shown in Fig. 2, and is intended to be. connected tothe air-hose leading to a suitable source oi compressed air, not shown. In the handle, 18.

there is the'usual control valve, not shown. which is operated by a llever .extending outside the handle, as indicated at 19,convenent to the operators hand.

In practice, the sawing apparatus requires two operators, one for each end of the` apparatus. The motors are connected to the respective casings on Aopposite -siciesl of the apparatus, soas to have the handle, 18, of each motor in the proper position tobe grasped by the right hand of the respectiveoperator, the left hand of the operator grasping the tubular handle 14,' which is on the opposite side of the respective casing. l

The saw blades employed as elements of the lnew sawing apparatus are of special construction, in that eachis given a predetermined curvature longitudinally, as indicated in Fig.'1`,so`

that when the blades are vput in close` contact with each other, back to back, as indicated in dotted lines in Fig. 7, and the respective ends of the blades securedto the corresponding crossheads, there is a'suiliciently strong lateral presf sure of each blade against'the other,'whereby L' they are maintained in close contact with each 61, are connected by a` cross-brace, I,12, which is put in place after the yokeshave been attached to the hubs of the respective casings. This crossbrace consists of two parts, held together by a boit, 1a, provided with a nut, as win be clear from i Fig. 3.

Each part has a nearly semi-circular jaw ateach-end and when the nut is tightened on the bolt, .13, the respective pairs of jaws clamp The lock-nut, 54, not only serves to lock the bearing support, 46,- against-a'ccidental rotation,

but also assists in retaining the split eye of the respective 'yoke-device `against 'lateral displacement. The lock-nut, 54, is used only on one of` the hubs of a casing, the 'opposite hub having, in place of the lock nut, a tubular'handle, 14,

which is threaded onto its hubon the side of the 4casing opposite `tol theside where the rotary nzotor is secured.l

`In one embodiment of the invention, each rof" tary motor is a one horse power vane type of air only, ythat is, away from `the back of the sawmotor,I normally operating atabout 350 revolutions per minute with an air pressure of about 70 ,pounds per square inch. Motors of this kind have a stalling torque of about 30 `foot-pounds -lis such motors are known and commercially obtainable, no specilc description of the ldetailsoi construction of such motor is given. However, the casing of vsuch a motor is modified somewhat to provide itwith means by which, it may be -attached in a convenient and readily removable `manner to the respective casing of the sawing` apparatus. As shown in Fig. 1, the motor casing T5, has a plurality of arms, 15, in this casethree,4

each provided-with a'hole at` its end, `so that by removing the nuts from three of the upper bolts, 22, which aid in holding the two halves of the casing together, the armsmay be put on said bolts .and the nuts replacedand screwed tight,

thereby securing the '-rotary'motor firmly to the said casing, in which condition the socket, X5, at the end of the motor shaft, engages the correother infone saw-kerf during the sawing operation, and hence. `cannot be spread apart or ,separated to sawseparate kerfs, by any variationsin hardness of the timber'which is being `sawed.

The backs of the' blades should be 'well polished.

In an apparatus of the present type, it is advantageous, in order -to avoid any tendency of the bladesl to separate, and, in fact, to increase the tendency to stay in close contact and at the -same time to give a-rapid cutting action, that thesaw-teeth of the blades be shaped in a par- Y ticular way, as will now bedescribed.

Each blade has a series of groups of teeth, each group-comprising two unset cutting teeth, a set cutting tooth and a planer tooth.; oril clearing tooth. A11 the unset cutting teeth have their ends orgpoints in a straight line, and all the planer or clearingy teeth have their ends in a line, but this line does not register with ,the line of the unset'cutting teeth, `because the planer teeth are shorter thantlie unset cuttingteeth. All the set cutting teeth are set in one' direction,

blade. Thesej teeth before setting, were of the same length as the unset cuttingteeth, but after setting have their ends in a linefwhich is outward from the vertical .plane of the outer face of vthe unset 'cutting teeth *and slightly above the level ofthe line of'the ends of the latter.

7 as a wedge, so that as the bladeis moved longil sponding endgof 'the drivingshaft, 58, of the sawing apparatus. 'l d y l The motor casing is provided with a suitable The unset cutting teethare beveled on the outer faces in both directions so a's to provide a sharp cutting edge in each direction of movementof the lsaw-blades, the bevel serving also spective set teeth and would tend, .by their wedge action, to crowd the saw-blade away from` its companion blade. However, thisdisadvantage is overcome by the wedge action of the greater number of beveled outer faces of the unset teeth.

Figs. 8 and 9 illustrate the construction reexample, in building or repairing docks and piers,

one blade to move such material is overcome by the tendency of the coacting blade to move the material in the opposite direction, these two reactions of the two blades always being equal and opposite. Of course, it is assumed that each of the two-blades cuts in both directions of movement, and that both blades cut equally in each direction. i In practice such a result may be at- 'tained because the teeth of each blade are arranged to cut in both directions and are identical with those of the companion blade.

By making the teeth of the blades as hereinbefore pointed out, with the'points of the cutting .teeth extending slightly below the line of v the points of the planer or plow teeth, and with the teeth similar in the two blades, the subthough, of course, it iinds application in other.

engineering work where compressed air is generally available for operating riveting, drilling or wood-boring machines such as are commonly known. The new apparatus, constituting the invention, takes advantage of the presence of airy compressing apparatus byv providing a compact power-operated sawing apparatus, replacing the -usual two-man crossi-cut saw and light enough to be handled readily by two men, while, at the same timegiving a rapidity of operation which will materially reduce the labor cost. It may be constructed so as to saw rapidly timbers as large as 20 inches square while, at the same Ytime by the use of modern lightky and strong metals or alloys, the weight of such apparatus 'need not exceed 50 pounds, which compares favorably with .the weight oi lother manually" handled power-operated tools now in use, vfor example, wood boring tools operated by compressed air and intended to be handled by one man, such a tool weighing 45 pounds.

It will be observed that with .the sawing apparatus of my invention, the only external reaction or stress, not counterbalanced within the apparatus itself, is the lateral stress due to the reaction of the two saws running in opposite drections, which tends tswing the respective casstantially equal but 'opposite longitudinal reactions of the two blades while sawing, are assured. It will be understood, that the size of the teeth may be as required for thework to be done, or the material to be sawed.

In order to obtain the desired ,predetermined tension on the blades after they have .been connected with their respectivel cross-heads. the yoke-devices are each subjected to a predetermined compressive Vstress in Ythe direction o'f moying the ends of the yoke-device toward each other, the compressive stress being within'the elastic limit for the yoke-device. The compresvsive force may be applied in any suitable way,

as by a screw-clamp or even with a so-called Dutch windlass, that is, a double cord or rope twisted by a bar inserted between thestrands,

or by a turn-buckle draw clamp. Whilefin the compressed condition the ends ofthe yoke devices are attached and rmly secured to the casings, after which the yoke-devices are freed lfrom the compressive stresses to which they have been subjected, and thereby the reactions of the yoke-devices are thrown upon the caslngs in the direction of separating themand thus tension o the saw-blades to the extent of the force due to the sum of the reactions of the two yoke devices, n

` which, of course, may be predetermined 'by the ings of the apparatus sidewise ilrstin one direction and then in the other. However, since the two saw bladesV run in close contact so that their two kerfs merge into one, and since the lever arm of the stress is merely the thickness of the bladeythis tendencyto cause a lateral swing is readily counterbalanced `by a slight resistance on the part of each man who has a relatively long leverage for the resistance tov lateral movement because of the widely separated handles, which he grasps. y A v Thus the lateral stress is vof little practical importance and may be disregarded. Asi e' from this lateral stress there are no external re ctions, if the apparatus is accurately built, because there i are four identical sets of epicycloidal gearings,

two sets of two gearings in each casing, the two in a casing` having the planet-wheels set with their respective axes of revolution diametrically opposite each other, as hereinbefore explained.

F thermore, -as Athere are two saw blades which are reciprocated in opposite directions, there is no tendency ofthe sawing apparatus Ato move in thev direction of the length of the saws, because the longitudinal reaction of one blade, as kit sawsa beam,or,th e like, is always opposite blade. Thus, there is no necessity for clamping the material to be sawed, for any tendency 'of amount yof compressive stress applied to the yoke-devices before putting them in place. 4The elastic reactions of the yoke-devices when in place are such as to exert a. pull .or tension on the saw-blades, that is, within the elastic limits' of the blades. The yoke-devices, or other mechanical device, will prevent the casings from being moved toward each other, except to the slight extent due' to the elasticity of the yoke devices, or other straining device, and the saw- .blade's prevent the casings from being moved away from each other. Thus the saw-blades and the straining device coact to maintain the casings-at substantially a vpredetermined distance apart. The `connections `between Y,the yoke-devices and the hubs of the casings are such as to allow for the slight variations in angle of the ends of the yoke-devices, due to the sligh spring` of the latter. T he methody of removing and replacing -sawblades'is as follows:

. The tension on the blades is relieved by ap.-

4plying a compressive force to the yoke-devices,

` in direction to the reaction of v.its companion in the manner hereinbefore explained. Then the cover cap, 65," at the end ofthe Vdrive shaft of one casing is removed and a hand crankap lplied'to the squared end of said shaft and actuated to move the cross-heads to the respectively opposite ends of their strokes, thus exposing L them enough outside the casings to allow the removal of one bolt foreach end of each saw f introduce new blades. I

A'from'the above explanation.

pairs of handles.l

inches.

blade. This being done, the hand crank is actuated -to bring the cross-heads to the position diametrically opposite that ,rst referred' to.

This exposesthe remaining bolt for each end of i' each blade, whichl bolts may then be removed,

thereby freeing the blades from their cross-- heads, for sharpening and replacement, or to The method of replacing the blades is obvious It is to be observed that in the `apparatus :shown inlFigs. 1 and 2 there can be no buckling of a blade due to thepushing action of one crosshead, because even if only one motor were operating, such.'motor when tending to cause a pushing 4action `on one blade, is causing a pull on'the other blade, and because of the tension This air in `expanding will have a cooling ellect, and serves `to assist in distributing lubricant to all parts of the gearing, because oil supplied 'to the compressed air motor, as is usual in practice, is gradually carried'oif as'a iine mist in the exhaust-and that portion which enters the `casing condenses inside 4the same, thus reaching the various parts of ,the gearing and lubricating it sulciently.

As hereinbefore described, the bearings for the Y sun-wheels may be adjusted in or out toward the ycentral plane yof the casing, and locked in y any adjusted position. Owing to the construction shown, this adjustability of `thesun-WheeIs toward and from each other makes it possible tc bring the backs of thesaw-blades accurately' 0 in the central verticalplane and even to deterdue to the pull on the latter blade, the gearing at the end opposite the'working motor is driven in synchronisin with the directly driven gearing k and thereby develops a pull on the blade which l Because of this action it is-not necessary to provide a f is being pushed `by the active motor.

very heavy xed tension on the saw blades by straining 4them with 'the yoke device.-

It is also to be noted that the two sets of saw-blades.

iced the saw 'downward while cutting, is `transepicycloidal gearingIin one casing r'un in unison e other casing, because the saw-blades form a xed connection between the four sets of gearing. As each motor drives not only its own two-sets of gearing but alsothe other twosets in the cas'- `with the two sets vof identical-gearing infthe ing opposite, because of the connection throughr thesaw-blades, which may be said to be alternately pulled and pushed by such motor.'y no difliculty can arise from starting one motor after another, as would naturally occur when on'e opi mine thepropcr'de'gree of pressure bctwecn said By means ol' th reaction due to theaverticalpressure exerted to mitted directly to the casing through the guides, thereby keeping such reactions off the gearings. It will be noted thatr the complete apparatus hereinbefore described is particularly intended for use in cross-cutting timber. For some purposes, such, for example, as ripping, or other vwork where `the yoke-devices might interfere, a diilerent form of. straining device maybeemployed.k One suitable structure is illustrated in Figs. 10 and 11. This comprises a metallic tubular bar, 90, to which are clamped two end-yokes.

l 9|, havingy split' eye portions, arranged to be vided with bearings to receive the. `journals of aV erator opens his motor air valve after the other 'Y operator has started his own motor. n

In a well constructed apparatus embodying the invention in its best form, there is no* vibration other than the trivial tendency to lateral -swinging of the casingsdue to the fact that the two saw-blades do notrun exactly in the same path, as has beeni previouslyv explained.` This tendencyI is easily counteracted without undue effort of the operators in holding their respective squeezed on the bar, 90, by bolts and nuts, indicated at;v 92. Each. endfyoke hasits ends prouniversal cross having, `as usual, four arms 93, 93a, 94, 94a, two, 93,93a, being mountedin thc respective bearings Ain the end yoke, whilethe other. two arms, 94, 94a, have links, 95, mounted on them, these links engaging the corresponding hubs off the respective 'casings.' The end yokes, 9| and universal crosses, are of such sizey that the axes of the journals connecting them lie in the plane ofthe backs 'ofthe saw-blades. The

By the particular combination of elements i hereinbefore shown and described, a remarkable i compactnes's is obtained. For exampleythe apparatus may be designed to cut timber measuring 18 inches along the kerf, and yet be within an out-to-out size of 51 inches, which is much shorter than the present two-man cross-cut hand-saw, used for cutting timber of the size mentioned above.

Although it is not n pull on the hubs of the respective casings,`trans mittedby the respective links may be made equal by having the arms, 94, 94a, of equal length. By applying a compressive stress to the two endyokes, 9|, tending to force them toward each t other,` al suitable lateral stress .of the straining bar, 9U, may be developed, this beingvkept within i the elastic limit of the. bar. Then when thedevice' is connected .tothe casing's, and the compressive force on the two end-yokes removedthe ecessary to have the ystroke ofthe blades equal to the maximum size of tirnber to be sawed, it probably is true that the eillciency is improved if the stroke is increased as the size ofl timber to be cut is increased. In the apparatus illustrated in the drawings, a tim- V bei- 18 inches 4across may be readily cut,even

though .the stroke of the saw blades'is only 12` While, as hereinbefore described,`vany suitable rotary motor may be employed, there are several importantadvantages inv theuseof a compressed air-motor, because its 'exhaust may be i used in part to blow the sawdust from the ker! and by its expansion to cool the blades. Another part maybe allowed to-entei-"theicasing, thus,

'causing a draft offair outward from the casing,

to prevent dust and dirt enteringI the casing.

light weight apparatus will naturally use shorter saw-blades; will inot require the.dcr ubleyoplce.V device and will not employ the curved blades.-

It will appear like Figal with the saw blades cut' oft` `lustto the left of the nozzle of lthe motor Vfor the right'hand casing and with the double i yoke-device and `its connectors detached, all the e guides for the cross-heads the of work, Yone casing, with its i In this way thel weight.

` ings with' their contained mechanisms, due to be noted that the links are connected to the hubs f ment of the casings and blades by' the tension K bination, with two saw-blades arranged to recipthe fact that the straining mechanism, whether for cross-cutting or for ripping, exerts its reaction uniformly on both hubs of-each casing. In putting the yoke-devices of Fig. 1 in place,

` as hereinbefore described; the split eyes connecting the yoke-devices to the hubs are loose, so that when the pre-tensioning means for the yok' devices are-removed, the reaction of the yokedevices tends'to dr'aw the casings apart and 'thereby to tension the saw-blades, while the connections of the yoke-devices tothe hubs are still loose. Hence,vr the casngs cannot be\sub jectedl to any twisting action by the deformation of the yoke-devices but occupy their proper position for proper alignment of the saw-blades and the cross-head guides. Thereupon, upon tight- 3 ening the split-eyes, the parts of the mechanism are held in their proper position.

The same action takes place when the straining mechanism ofFig. 10 is employed. It will 3 of. the casing by split eyes. By having these loose while assembling the straining mechanism, and until after the pre-tensioning devices are removed, the reaction of the straining mechanism pulls all parts into proper alignment, whereupon the various split eyes of the mechanism maybe tightened to hold all parts rigidly.

',The construction of the yoke-device of Fig. 1 is such that each yoke may be swung down from its vertical position to a position where both yokes are in a horizontal plane, this being possible because of the screw-thread connection shown at 11. In' doing this the bolts 'I0 and 'Il are loosened, which insures -the proper alignof the latter. 'Ihen the split eyes and connectors may be screwed up to hold theA parts rigidly. What is claimed is: 1. In a portable sawing apparatus, the co'mrocate longitudinally with their backs in contact with-each other, and to cut equally in each direcjtion, of four sets of identical epicycloidal gearings, each arranged to convert rotary motion into reciprocating motion, each being connected to the respective end of its respective saw-blade, two

-sets of said gearings vbeing arranged near one end of the sawing apparatus opposite each other with the saw blades between them and the other two sets near the other end of the sawing apparatus 65 opposite eachother with the saw-blades between them, and a com'mon drive -mechanism for each' two sets of gearings.

2. Inv a portable sawing apparatus, the com-- bination, with viour sets of identical epicycloidal gearings each arranged to convert rotary motion intdreciprocatory motion, and two' saw-blades arrangedwiththeir backs in contact, each having its'two ends connected to two sets of said gearing for longitudinal reciprocation, oneset of 7 gearing at each end, the four sets of gearing being symmetrically arranged with respect tothe plane through the backs of said saw-blades, gearing common to each two sets of gearing at each 5v end of the blades for maintaining all the gears in unison, and power means for driving at least one of said common gearings.

3. In a portable sawing apparatus, the c ombination, with two saw-blades, each vhaving a O preformed curve longitudinally, convex on the back of the blade, said blades being arranged to ingconnected to the respective end of its ref spective saw-blade, two sets of said gearings being arranged near one end of the sawing apparatus opposite each other with the saw-blades between them and the other two sets near the other end of the sawing apparatus opposite each other, with the saw-blades between them, a common drive vmechanism for each two sets of gearings, and resilient means having a predetermined compression for holding the two sets of gearings at one end of the apparatus in spaced relation t'o the two sets of gearing at the other end of the apparatus to tension the blades longitudinally. 0.

bination, with two saw-blades, each having a preformed curve longitudinally, convex on the back of the blade, said blades being arranged to reciprocate longitudinally with their backs in contact 5y with each other, and to cut equally in each direction, of four sets of identical epicycloidal gear- `ings, each arranged to convert rotary motion into reciprocating motion, each being connected to the respective len d of its respective saw-blade,.- 40 two sets of -said gearings being arranged near one end of the sawing apparatus opposite each( other with the saw-blades between them and the other..

twosets near the other end of the sawing apparatus opposite each other, with the saw-blades between them, a common gearing for veachtwo sets of'gearings whereby they are compelled to rotate in unison, means for driving at least one of said common gearings, a resilient yoke-device t having a predetermined compression arranged to4 act -in 'cooperation with the saw-blades to hold preformed curve longitudinally, convexcn the back of the blade, Vsaid blades being arranged to reciprocate longitudinally with their backs in contact wi-th each other, and to cut equally in each direction," of four sets of identical epicycloidal gearings, each arranged to convert rotarymotion into reciprocating motion. each being connected to the respective end of its respective saw-blade, 'two vsets of said gearings being arranged near one end of the ksawing apparatus opposite each other with the saw-blades between them andthe other two sets near the other end of the Asawing apparatus fopposite each other, with.Y the saw-blades between them, a common drive mechanism for each two sets of gearings,

and a pair of yoke devicesl coacting to hold the.

two sets of gearing at one end .of the apparatus in spaced relation tothe two sets of gearing at 6 theother end of the apparatus, said yoke de- 4. In a portable sawing apparatus, the cornl 5. In a portable sawin'g apparatus, the coml bination, with two saw-blades, each having a vices being adjustable into erect-planes and also into planes atan angle to the erect planes. Y

6; In a portable sawing apparatus, the comwith each other, and to ,cut equally in each direc'- tion, of two sets of identicalV epicycloldalgear-y ings, each arranged to reciprocate its respective saw', said sets being arranged opposite each other 'on opposite sides of the ends of the two saws, and

a rotary compressed air motor arranged to drive substantiauy the same amount of longitudinal Y bination, with two saw-bladesv arranged to reciprocate longitudinally with their backs in contact botlii sets of gearings and to discharge its -ex-r being positioned on itssun-wheel at all times in diametrically' opposite relation to that of the planet-wheel of the other set,' of means for drivblades, whereby the total length of the `appara.-`

reaction as that'of its companion blade.

9. In a portable sawing apparatus the comblnation, with two identical saw-blades arranged contact with each other and to cut equally in each direction of movement, of two identical sets of gearings, one for each'blade, each set being arrangedto reciprocate its respective saw-blade in,

a direction of movement at all times opposite to that of its companion blade and alwaysfat each instant, with a rate of movement equal to that of its companion blade, said sets of gearing being arrangedl opposite each other with an intervening space between them to receive the .corresponding ends and cutting vportions of said sawtu's is reduced, While allowing a full stroke for the blades, and means for driving both sets `of gearing in unison. f i

l0. In a portablesawing apparatus, the combination, with a pair of sets of identical epicycloidal gearing, each set comprising'a sun-wheel,

, to reciprocate longitudinally with their backs in l a planet-wheel revoluble about an axis carried around by the sun-wheel, and means for rotating i the planet-wheel about its said axis at vtwice the ing the two sun-Wheels in unison, a 'pair of cross- Y.

heads; a pair of driving pins, `each of which iS mounted on its respective planet-wheel with its axis normal to the planeof rotation of its planetwheel and intersecting the'pitch-line of the latter, said driving pins being Journaled in the re. spective cross-heads and arranged to bring simultaneouslythe'respective cross-heads to the relatively opposite extreme-ends of ,their respective strokes, guides located between the two sets of epicycloidal gearingsand arranged to guide the respective cross-heads rectilinearly, and ,a

pair of saw-blades, each connected to its respective cross-head, eachblade being provided with teeth for cutting `equally in each direction of movement of the blade and arranged to produce at all times substantially the same amount of longitudinal reaction as that of its companion blade.

8. In a portable sawing apparatus, the combination, with a pair of sets of identical epicycloidal gearings, each set comprising a sun-wheel,

rate of rotation of `the sun-wheel, said `sets of gearing being arranged `directly opposite each other, with the central axes of their sun-wheels in alignment, and with the axes of the planet-4` wheels diamctrically opposite each' other, `said sets being spaced apart to provide a runway for Vsaw-blades, stationary'guideways located in said runwayf-space between the gearings parallel to` the diameters of the sun-wheels, 4and a pair of cross-heads movable in said guides and arranged totravel across the common axial lineof the sun-.wheel`centers from oneA side toithe other' side of it, .of a common drive for rotatingthe sun-wheels in unison, means carried -by each planet-wheel and pivotally connected to its respective cross-head for reciprocating the crosshead in its respective guideway, and a pair of I Aidentical sawblades,- each connected to its rea planet-wheel revolubly mounted on said sunwheel, and -a xed internal circular rack meshing with the planet-wheel, `the pitch diameter of the planet-wheel being one-half that voi? said circular rack, the axis of rotation of one planet-wheel of on its sun-wheel at all times in diametrically opposite relation to'that of the planet-wheel of the one set of epicycloidal gearing being positioned other set, of means for driving the two sun-wheels in unison, meanstor adjustinglthe sun-wheels toward and from each other, a pair, of crossheads, a pair of 'driving pins, each' of which is spective cross-heads andarranged to bring simultaneouslythe respective cross-heads to the rela-y tively. opposite extreme ends. of their respective strokes, guides located 'between the two sets o f y epicycloidal gearin'gs and arranged to guide the respective cross-heads `rectiliriearly, Vand a vpair of'saw-blades, 4eachconnected toits respective cross-head, each blade being provided with teeth` for cutting equally in eachv direction or movement of thevbladeand arrangedt produce at all times. 75

mountedon its respective planet-wheel with its axis normal to the plane ,of rotation of its planetwheel and intersecting the pitch-line of. the latter, said' driving pins being journaledinftherei spective cross-head with the backs of the blades in contact, each `blade beingprovided with teeth for cuttingequally in each direction of movement of the blade and arranged to produce at all times substantially the same amount of longitudinal reaction as that of its companion blade.

11. Inatportable sawing apparatus, the combination, with four sets of identical epicycloidal gearing,` each set Vcomprising a sun-wheel, a

.planet-Wheel revoluble about an axisl carried around by the sun-wheel, and means for rotating A, the planet-wheel'about its said axis at twice the r-ateY of rotation of the sun-wheel, said setsof gearing beingarranged inpairs at opposite endsv of the apparatus, the sets of gearing of each pair` being arranged directly opposite each other, with the central axes or their sun-wheels in alignment, and theaxesof their planet-wheel diametrically opposite each other, saidsets `of gear` I ingo! each pair being spaced apart to provide a runway for saw-blades', stationary` guideways loi `cated in 'each or said runway-,spaces between, the respective pairs oi.' gearings parallel to the diameters of the corresponding' sun-wheels, anda pair of cross-heads for each pair of setsof gearing movable in the respective guidesV and arranged totravelacross the common axial line of the respective sun-wheel centers from one side to the other sldeof it, of a common drive -or ro-` tating each pair of sun-wheels in. unison, means carried by each planet-wheel and pivotally oon-.

direction of movement of the blade and arrangedAY to produce at all times substantially the same amount of ongitndinal reaction as that of its 'companion blade. p

12. In a portable sawing apparatus, the coml bination, with four sets of identical epicycloidai gearing, each set comprising va sun-wheel, a planet-wheei revoluble about an axis carried around by the sun-wheel, and( means for rotating the planet-Wheelabout its said axis at twice the rate of rotation of the sun-wheel, said sets of gearing being arranged in pairs at opposite ends of the apparatus, the sets of gearing of eacii pair being arranged directly opposite each other, with the central axes of their' sun-Wheels in aiign= mena and Witlothe axes of their planet-Wheel diametricaily opposite eachother, said sets of gearing of each pair being spaced apart to provide a runway for saw-blades, stationary guide Ways located in each of said runwayspaces between the respective pairs of gearirigs parallel to the diameters of the corresponding sunwwheeis, and a pair of cross-heads for each pair of sets of gearing movable in' the respective guides and arranged to travel across the common axial line of the respective sun=wheel centers from one side to the other side" of it, of a common drivel for rotating each pair of sun-fvvneelsin unison, means carried by eaciiu planet-Wheel and pivotaily con? nested to itsrrespective cross-head for reciprocaty ing the cross-head .in its respective guideway, a

pair of identical sawblades, each connected at each end to its respective cross-heaci-with the` backs of the blades in Contact, each blade being provided with teeth ier cutting equaiiy in eacn direction of movement ci the 'blade and arranged to produce at all. times substantialiy the sarne' amount of longitudinal reaction .as that of its companion blade, and resilient means for holding the respective pairs of 'gearings apart to teria sion the bladea y EDWARD DE VCE TOMPKINS. 

